package com.chen.demo.javase.algorithm.leetcode.editor.cn;

//将两个升序链表合并为一个新的 升序 链表并返回。新链表是通过拼接给定的两个链表的所有节点组成的。 
//
// 
//
// 示例 1： 
//
// 
//输入：l1 = [1,2,4], l2 = [1,3,4]
//输出：[1,1,2,3,4,4]
// 
//
// 示例 2： 
//
// 
//输入：l1 = [], l2 = []
//输出：[]
// 
//
// 示例 3： 
//
// 
//输入：l1 = [], l2 = [0]
//输出：[0]
// 
//
// 
//
// 提示： 
//
// 
// 两个链表的节点数目范围是 [0, 50] 
// -100 <= Node.val <= 100 
// l1 和 l2 均按 非递减顺序 排列 
// 
// Related Topics 递归 链表 
// 👍 1476 👎 0

import java.util.Scanner;

public class MergeTwoSortedLists {
    public static void main(String[] args) {
        Solution solution = new MergeTwoSortedLists().new Solution();
        ListNode l1 = initList("第一个链表");
        ListNode l2 = initList("第二个链表");
        ListNode mergerResult = solution.mergeTwoLists(l1, l2);
        printList(mergerResult);
    }

//leetcode submit region begin(Prohibit modification and deletion)

    /**
     * Definition for singly-linked list.
     * public class ListNode {
     * int val;
     * ListNode next;
     * ListNode() {}
     * ListNode(int val) { this.val = val; }
     * ListNode(int val, ListNode next) { this.val = val; this.next = next; }
     * }
     */
    public static class ListNode {
        int val;
        ListNode next;

        ListNode() {
        }

        ListNode(int val) {
            this.val = val;
        }

        ListNode(int val, ListNode next) {
            this.val = val;
            this.next = next;
        }
    }

    public static ListNode initList(String listNo) {
        System.out.println("链表长度:");
        Scanner scanner = new Scanner(System.in);
        String s = scanner.nextLine();
        int length = Integer.parseInt(s);
         ListNode head = null;
         ListNode temp = null;
        System.out.println("以此输入链表数据:");
        while (length > 0) {
            if (head == null) {
                temp = new  ListNode(Integer.parseInt(scanner.next()));
                head = temp;
            } else {
                temp.next = new  ListNode(Integer.parseInt(scanner.next()));
                temp = temp.next;
            }

            length--;
        }
        return head;
    }

    public static void printList(ListNode head) {
        ListNode temp = head;
        while (temp != null) {
            System.out.print("" + temp.val + " ");
            temp = temp.next;
        }
        System.out.println("");
    }

    class Solution {
        public ListNode mergeTwoLists(ListNode l1, ListNode l2) {
            if (l1 == null) {
                return l2;
            }
            if (l2 == null) {
                return l1;
            }
            ListNode head = null;
            ListNode tmp;
            ListNode tail = null;
            while (l1 != null && l2 != null) {
                // l1 向后移动
                if (l1.val <= l2.val) {
                    tmp = l1;
                    l1 = l1.next;
                } else {
                    // l2 向后移动
                    tmp = l2;
                    l2 = l2.next;
                }
                if (head == null) {
                    head = tmp;
                    tail = tmp;
                } else {
                    tail.next = tmp;
                    tail = tail.next;
                }
            }
            if (l1 != null) {
                tail.next = l1;
            }
            if (l2 != null) {
                tail.next = l2;
            }
            return head;
        }

    }
//leetcode submit region end(Prohibit modification and deletion)

}